<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://unpkg.com/react@17/umd/react.production.min.js" rel="external nofollow" rel="external nofollow"></script>

    <script src="https://unpkg.com/react-dom@17/umd/react-dom.production.min.js" rel="external nofollow" rel="external nofollow"></script>

    <script src="https://unpkg.com/babel-standalone@6/babel.min.js" rel="external nofollow" rel="external nofollow"></script>
</head>
<body>
    <div id="test"></div>
    <script type="text/babel">
class Demo extends React.Component{
    render(){
         return(
             <div>
                <input ref="input1" type="text" placeholder="点击按钮提示数据"/>
                <button onClick={this.showData}>点击提示左侧的数据</button>
                <input ref="input2" onBlur={this.showData2} type="text" placeholder="失去焦点时触发"/>
                </div>
         )
    }  
    showData=()=>{
    // const input=document.getElementById('input1');
    // alert(input.value);
    console.log(this);
    console.log(this.refs.input1);
    // console.log(this.refs.input1.value);
    alert(this.refs.input1.value);
    
}
    showData2=()=>{
const{input2}=this.refs;
alert(input2.value);
}
}

ReactDOM.render(<Demo/>,document.getElementById('test'));
    </script>
</body>
</html>